1. Field of the Invention
The invention relates to an overburden excavator with a gantry arm which can be adjusted vertically and pivoted laterally, and with rotary cutters with cutting edges located on both sides of its receiving conveyor.
2. Description of the Prior Art
On an overburden excavator of the prior art as described in DE-AS 11 39 073, the axis of rotation of the rotary cutters is perpendicular to the conveyor belt, and the rotary cutters have excavating blades for the overburden, whereby the working directions of the rotary cutters can be opposite to one another. When the direction of the rotary cutters is from top to bottom, there must be extra space below the gantry for the idler rolls and the conveyor belt. If some of the material cut off remains ahead of the front end of the gantry and is not transported onto the conveyor belt, this material left on the ground hinders the movement of the rotary cutter on the other side when the gantry pivots laterally. This is also true in the opposite direction of rotation, i.e. when the rotary cutters are operating from bottom to top. This overburden excavator of the prior art is apparently suitable only for use in rather loose ground, because the overburden material is further compressed after it is removed. It is unsuited, moreover, for cutting and breaking hard rock.